CIRCUIT BOARD FOR ELECTRONIC DEVICE

摘要

PROBLEM TO BE SOLVED: To obtain a circuit board which allows high-density packaging by filling through holes for electrically connecting the top face and bottom face of a circuit board with resin and setting the resin face exposed at the through hole face substantially flush with the copper pattern face surrounding the through holes. SOLUTION: A through hole 4 is filled with UV-curing resin 6 and a projection 12 is formed on both the sides of the base material 2 of a substrate. The UV-curing resin 6 filled in the hole is exposed to UV until it is partially cured. Then curing operation is suspended. The projections 12 of the UV-curing resin 6 are shaven and flattened and at the same time the copper 5 is also uniformly shaven to uniformly reduce the thickness of the copper 5. The UV-curing resin left unshaven is heated and fully cured. Thus, a high-density wiring patterns are obtained with ease.